I am playing with C# web services on Linux using Mono version 1.0.  I
am attempting to create a telnet web service.  I am trying to use the
/bin/login process and connect to its standard input and output as
follows:

          ProcessStartInfo psI = new ProcessStartInfo("/bin/login");
          psI.UseShellExecute = false;
          psI.RedirectStandardInput = true;
          psI.RedirectStandardOutput = true;
          psI.RedirectStandardError = true;
          psI.CreateNoWindow = true;

          //psI.Arguments ="/bin/login";

      ProcessData pd = new ProcessData();

      pd.p = new Process();
          pd.p.StartInfo = psI;


          pd.p.Start();
          pd.sw = pd.p.StandardInput;
          pd.sr = pd.p.StandardOutput;
          pd.err = pd.p.StandardError;

I then later try to read and write to the process
if(pdata.sr.Peek() != -1)
{
 return pdata.sr.ReadToEnd();
}
return pdata.err.ReadToEnd();



and
pd.sw.WriteLine(theData);

I am getting no output data from the login process, and sending input
results in the following error:
The remote server returned an error: (500) Internal Server Error.
Win32 IO returned ERROR_NO_MORE_FILES. Path: [Unknown]

Why can I not get I/O to this process

---

Request for Question Clarification by maniac-ga on 16 Jul 2004 17:30 PDT

Hello Bjschnei,

Hmm. If you change
  /bin/login
to something like
  /bin/ed  (or some other interactive program)
does the code you are describing work as expected?

I'm assuming your code is basically correct but there may be special
case code in /bin/login that prevents you from "spoofing" the
connection. I can suggest alternative methods based on the results of
the test I suggest above.
  --Maniac

---

Clarification of Question by bjschnei-ga on 16 Jul 2004 20:25 PDT

I wrote a simple test program that excepted data, and echoed it
back...that worked fine. i changed the process to /usr/bin/telnet, and
as an argument passed it localhost which i have found some confusing
results.

When using telnet as the code is now, I get the expected data, which
ends with a login prompt -> but there is an extended delay.  If i then
try to putData, supplying the username, i get the ERROR_NO_MORE_FILES

if i change getData to return 1 character at a time, and in the middle
of getting characters, make a call to putData, i don't get the error
-> haven't played with it enought to see what is causing this
behavior..getting kind of frustrated with it so i needed a brake..i.e
google answers..but anyway..what appears to be happening here, is that
ReadToEnd is not returning until telnet app ends(telnet must be timing
out)..and then when i try later write to it, it fails...not sure why..

in anycase, reading one char at a time with /bin/login results in no
data, and i can't send any either...

playing with /bin/login, i have concluded that the only way i can run
it from an existing shell(xterm) is by using the command: exec
/bin/login ...which really doesn't help much because i can't call exec
from my web service....

---

Request for Question Clarification by maniac-ga on 17 Jul 2004 18:15 PDT

Hell BjSchnei,

I suspected some odd behavior with /bin/login and your clarification
confirms it. Let me provide some background:

The program /bin/login (for Linux), as documented in
  man login
or on line at:
  http://www.die.net/doc/linux/man/man1/login.1.html
[go to the "bugs" section]
describes the method used to ensure you don't password sniff [uses
vhangup]. There are also a number of checks [see earlier sections]
that verify that the "terminal" you are using is acceptable for
connections / the user name supplied. I don't know what C# uses under
the hood for connections to standard input / output but I'll guess
pipes - they appear to be unacceptable for /bin/login.

Your use of telnet appears to get you farther but still does not do
the job. A couple solutions come to mind:

[1] Review the source code for the server side of rlogin, rsh or
telnet. For example:
http://www.rpmfind.net//linux/RPM/PLD/dists/ra/PLD/i386/PLD/RPMS/rlogind-0.17-4.i386.html
has the source to the rlogin daemon. Be sure to get the source RPM. If
you don't use an RPM based distribution, let me know so I can give you
instructions for another Linux distribution. You can then do the
similar method in C# to get the same behavior.

[2] Use pseudo terminals (or pty's). You would make a connection to
the master side of a pty and /bin/login runs on the slave side. In
this case, /bin/login can still do all the terminal specific actions
and your program can handle them. I know xterm uses this method but it
can be very complicated to set up.

Let me know if you want to pursue one or both of these methods.
  --Maniac